/Engine/Source/Runtime/GeometryCore/Public/Util/RefCountVector.h
Returns iteration object over mapping applied to valid indices eg usage: for (FVector3d v : mapped_indices(fn_that_looks_up_mesh_vtx_from_id)) { ... }
template<typename ToType> [MappedEnumerable](API\Runtime\GeometryCore\Util\FRefCountVector\MappedEnumerable)< ToType > MappedIndices ( [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< ToType(int)> MapFunc ) const